TW201930062A - A composite material for a flexible printed circuit board and preparing method thereof - Google Patents

Abstract

A composite material for a flexible printed circuit board (FPC) includes a pressure-sensitive adhesive-backed flexible copper foil substrate and a high-frequency high-transmission double-sided copper foil substrate. The flexible copper foil includes a third copper foil layer, a second insulating layer, and a second extremely low dielectric adhesive sequentially. The high-frequency high-transport double-sided copper foil substrate includes a first copper foil layer, a second copper foil layer, and a core layer in between. The inner surface of the first copper foil layer has a Rz value of 0.05 to 0.5 [mu]m, and the inner surface of the second copper foil layer has a Rz value of 0.1 to 1.10 [mu]m. The composite material used in the flexible printed circuit board (FPC) of the present invention has a simple structure and exhibits great electrical properties, such that a benefit of low cost, short manufacturing process, low coefficient of thermal expansion, stable Dk/Df performance in a high temperature and humidity environment, ultra-low water absorption, great UV laser drilling ability, low rebound force and suitable for high-density assembly and excellent mechanical properties can be obtained.

Description

Composite material for flexible printed circuit board and preparation method thereof

The present invention relates to an FPC (Soft Printed Circuit Board) and a method of fabricating the same, and more particularly to a composite material for a flexible printed circuit board and a method of making the same.

With the rapid development of information technology, in order to meet the high-speed high-speed signal transmission, rapid heat conduction and heat conduction, and the lowest production cost, the design and application of various forms of mixed-pressure structure multi-layer boards are in the ascendant. Printed circuit boards are an indispensable material in electronic products, and as the demand for consumer electronics grows, so does the demand for printed circuit boards. Due to the flexible and flexible three-dimensional wiring of flexible printed circuit boards (FPC), it is widely used in the development of technology-based electronic products that emphasize lightness, shortness, flexibility, and high frequency. Applications of computers and peripherals, communications products, and consumer electronics.

In the high-frequency field, wireless infrastructure needs to provide low enough insertion loss to effectively improve energy efficiency. With the advent of 5G communication, millimeter wave, and aerospace military to accelerate the demand for high-frequency FPC/PCB (printed circuit board), with the rise of emerging industries such as big data and Internet of Things, and mobile interconnect terminals Popularize and process and transmit information quickly, becoming the focus of the communications industry. In the field of communication, the future 5G network has a higher speed bandwidth and more dense micro base station construction than 4G, and the network speed is faster. With the demand for Internet of Things and cloud computing and the new generation of broadband communication, the development of high-speed servers and higher transmission rate mobile phones has become a market trend. In general, FPC/PCB is the main bottleneck in the entire transmission process. If there is a lack of good design and electrical related materials, the transmission rate will be seriously delayed or the signal loss will be caused. This puts high demands on the board material. In addition, the high frequency sheet materials currently used in the industry are mainly LCP (liquid crystal polymer) sheets and PTFE (polytetrafluoroethylene) fiber sheets. However, they are also limited by the process technology, have high requirements for manufacturing equipment and need to be in a relatively high temperature environment. (More than 280 ° C) can be operated, which also causes uneven film thickness, uneven film thickness will cause the impedance of the circuit board to be difficult to control, and the high temperature pressing process will cause LCP or PTFE extrusion to affect the plating. The continuity of copper forms an open circuit, which leads to poor reliability and reduced reliability. In addition, it is difficult to use because of the inability to use fast press equipment. In addition, in SMT (surface mount) high temperature process or other FPC process, for example When bending, strong acid and alkali solution, the strength is insufficient, resulting in a decrease in yield. However, although other resin film layers do not have the above problems, they also face problems such as poor electrical properties or poor mechanical strength.

The composite substrate is proposed in the Chinese Patent No. 201590948 U, the Taiwan Patent No. M377823, the Japanese Patent No. 2010-7418A, and the Japanese Patent No. 2011/0114371, and the Chinese Patent No. 202276545 U, No. 103096612 B China The patent, the Taiwanese patent No. M422159 and the Taiwanese patent No. M531056, the high frequency base is made of fluorine-based materials. Board, however, there is still a need in the industry to develop novel double-sided copper foil substrates to solve the above problems.

The signal integrity is very important in high-frequency high-speed transmission. The main factors affecting are the copper foil layer and the insulating polymer layer substrate. The raw material of FRCC as the FPC/PCB board is mainly composed of multiple layers of insulating polymer layer and copper foil layer. The performance of FRCC is highly dependent on the choice of lower dielectric constant/dielectric loss resin layer and the choice of copper foil surface roughness and lattice arrangement.

In order to solve the above technical problems, the present invention provides a composite material for a flexible printed circuit board (FPC), comprising: a high frequency high transmission double-sided copper foil substrate having a first copper foil layer, sequentially formed in the first a core layer on the surface of the copper foil layer and a second copper foil layer, wherein the material forming the core layer is LCP resin or polyimine; and a backing soft copper foil substrate (FRCC) having a thickness of 8 to 185 μm a third copper foil layer having a thickness of 1 to 35 μm, a second insulating polymer layer having a thickness of 5 to 100 μm sequentially formed on the surface of the third copper foil layer, and a thickness of 2 to 50 μm. a second very low dielectric adhesive layer, and the adhesive backed flexible copper foil substrate is pressed into the high frequency high transmission double-sided copper foil substrate by the second extremely low dielectric adhesive layer; wherein the second insulating polymerization is formed The material of the layer is at least one of the group consisting of polyimine and LCP resin; the dielectric constant (Dk value) of the second low dielectric layer is 2.0 to 3.50, and the dielectric loss (Df value) The surface roughness of the surface of the first copper foil layer and the second copper foil layer adjacent to the core layer is respectively 0.002 to 0.010; 0.05 to 0.5 microns and 0.1 to 1.10 microns.

Preferably, when the second insulating polymer layer is a polyimide layer, the thickness It is 5 to 50 μm; when the second insulating polymer layer is an LCP resin, the thickness is 5 to 100 μm.

In one embodiment, the water-repellent rate of the backed flexible copper foil substrate is 0.01 to 1.5%.

In one embodiment, the first copper foil layer, the second copper foil layer, and the third copper foil layer are independently selected from the group consisting of a rolled copper foil layer or an electrolytic copper foil layer.

In one embodiment, the LCP resin has a dielectric constant (Dk value) of 2.0 to 3.50 and a dielectric loss (Df value) of 0.002 to 0.0050.

In one embodiment, the second insulating polymer layer and the third copper foil layer and the second very low dielectric adhesive layer have a bonding strength greater than 0.7 kg force/cm.

In one embodiment, the material for forming the second ultra-low dielectric layer is selected from the group consisting of a fluorine resin, an epoxy resin, an acrylic resin, a urethane resin, a ruthenium rubber resin, and a poly pair. At least one of a group consisting of a cycloxylene resin, a bismaleimide resin, and a polyamidene resin.

In a specific embodiment, the second very low dielectric adhesive layer is a thermosetting polyimine layer containing polyiminoimide, and the polyamidimide content in the second very low dielectric adhesive layer is The second very low dielectric layer has a total solids weight of 40 to 95%.

In one embodiment, the adhesive back flexible copper foil substrate further comprises another extremely low dielectric adhesive layer formed between the third copper foil layer and the second insulating polymer layer, and the third copper The total thickness of the foil layer, the other very low dielectric adhesive layer, the second insulating polymer layer and the second very low dielectric adhesive layer is 10 to 185 microns.

In a specific embodiment, the material of the second insulating polymer layer formed in the adhesive copper foil substrate is polyimine, and the total thickness of the backed flexible copper foil substrate is 8 to 135 micrometers.

In a specific embodiment, the high-frequency high-transmission double-sided copper foil substrate further comprises two first-pole low-dielectric adhesive layers formed on opposite surfaces of the core layer to be respectively located in the first copper The material between the foil layer and the core layer and between the second copper foil layer and the core layer, and the material of the core layer is polyimine.

The present invention provides a method for preparing a composite material for a flexible printed circuit board (FPC), comprising: pre-pressing the high-frequency high-transmission double-sided copper foil substrate and a backing soft copper foil substrate; and pressing and aging the high The high-frequency transmission double-sided copper foil substrate and the adhesive back flexible copper foil substrate, wherein the pre-pressing time is 10 to 30 seconds, the molding time is 120 to 180 seconds, and the molding pressure is 90 to 110 kgf/cm ² , and the pressing temperature is The aging temperature is 165 to 175 ° C and the aging time is 50 to 60 minutes.

According to the invention, the composite material for a flexible printed circuit board (FPC) has at least the following advantages:

1. The composite material for a flexible printed circuit board (FPC) of the present invention is formed by FRCC and a high frequency high transmission double-sided copper foil substrate, and has three layers of copper foil layer after pressing, wherein the third copper foil layer And the second copper foil layer is a copper foil layer on the outer side, which requires high temperature (about 260°) soldering and components, so the peel strength of the two is required to be high (greater than 0.7 kg force/cm), and the first copper foil The layer is an inner copper foil layer located in the middle, also called the signal copper foil layer, which is mainly used for the conduction line, and does not need to be loaded with components by SMT or other high temperature processes. Therefore, the peel strength of the first copper foil layer and the second pole low dielectric adhesive layer is required to be lower, and only needs to be more than 0.5 kg force/cm. In the conventional concept, the copper foil layer and other layers in the FPC have been considered. Then the strength is larger in a certain range (at least greater than 0.7 kg force / cm), the less easy to delamination, the large bonding strength generally requires a large Rz value of the copper foil layer, and the signal transmission process of the copper foil layer With the skin effect, in order to achieve high frequency and high transmission, the Rz value of the copper foil layer needs to be as small as possible, so there is a contradiction between the large bonding strength and the high frequency and high transmission, and the FPC of the present invention is due to the first copper foil. The layer does not need to be loaded with SMT or other high-temperature process components, so the peel strength of the first copper foil layer and the second very low dielectric adhesive layer is relatively low, and only needs to be greater than 0.5 kg force/cm, so the first The copper foil layer can select a copper foil layer with lower Rz value, better electrical conductivity, and lower insertion loss, and does not affect the high frequency and high transmission property of the FPC.

Second, the third copper foil layer, the first copper foil layer and the second copper foil layer of the invention have low surface roughness (Rz) values, and have a skin effect during signal transmission, because the surface roughness of the copper foil is relatively Low, fine crystal, good surface flatness, so the signal can achieve high-speed transmission, while the low dielectric layer has low and stable Dk/Df performance, which can reduce the loss during signal transmission and further improve the signal transmission quality. It is fully capable of FPC high-speed, high-speed heat dissipation and rapid development of production costs.

3. The second very low dielectric adhesive layer of the present invention refers to a rubber layer having a Dk value of 2.0 to 3.5 and a Df value of 0.002 to 0.010, and a low Dk/Df value which is stable in a high temperature and humidity environment, The invention makes the FRCC and the high frequency high transmission double-sided copper foil substrate suitable for rapid pressing at low temperature (less than 180 ° C) to obtain the invention The FPC has strong processability, low requirements on production equipment, and thus lowers production cost. Its equipment operability and processability are superior to existing LCP substrates and PTFE fiberboards; more preferably, it is suitable for low temperature pressing. The risk of line oxidation during the preparation of FPC is reduced.

4. The second very low dielectric layer of the present invention may be a thermosetting polyimine layer containing a polyimine, and the content of the polyimine is 40 to the total solid content of the extremely low dielectric layer. 95%, using a thermosetting polyimine layer with an insulating polymer layer structure, the double-sided copper foil substrate of the present invention has a smaller pore diameter (less than 100 micrometers) which is more suitable for the downstream industry than the conventional epoxy resin product. ) Ultraviolet laser processing, it is not easy to cause PTH (Plating Through Hole) or hole retraction, uniform film thickness during pressing, good impedance control, not only suitable for machining with large aperture mechanical drilling, process adaptation Stronger.

5. The FRCC of the present invention has a lower rebound force than the ordinary LCP board, and is only about half of the rebound force of the LCP board, and is suitable for the downstream high-density assembly process.

6. The second insulating polymer layer of the FRCC of the present invention may be a polyimine layer, and the second very low dielectric layer may contain a polyimine in the formulation, and the overall water absorption of the present invention is 0.01 to 1.5. %. Due to the ultra-low water absorption rate, stable performance after water absorption, and better electrical performance, the risk of bursting of the multi-layer board and the soft and hard board can be greatly reduced, and the signal transmission insertion loss is reduced.

7. The flexible printed circuit board (FPC) of the present invention has the advantages of good thermal expansion property, good flexibility, high solder resistance and excellent mechanical properties, and the adhesion strength of the extremely low dielectric adhesive layer is good. And then the intensity is greater than 0.7 Jin / cm.

8. At present, the coating type LCP substrate can only be coated with a thickness of about 12.5 micron, and the preparation of the 50 micron thick LCP substrate requires four coatings, and if the LCP high frequency high transmission double-sided copper foil substrate is to be prepared. The process of pressing the copper foil layer on the other side is also required, and the process is complicated and inefficient. The present invention can use a three-layer structure of a polyimide layer for FRCC, and the polyimine layer can be coated once, so that the present invention Further, the FPC of the above structure has a simple preparation process and has a cost advantage.

9. When the current Bond Ply product is used in the downstream industry, it needs to peel off the release layer and then press the copper foil layer. However, using the FRCC (Flexible Resin Coated Cooper) structure of this structure, the structure is simple. It can save downstream processing steps and is relatively inexpensive.

100‧‧‧Adhesive soft copper foil substrate

101‧‧‧ third copper foil layer

102‧‧‧Second very low dielectric adhesive layer

1021‧‧‧Another very low dielectric layer

1022‧‧‧Second very low dielectric adhesive layer

103‧‧‧Second insulating polymer layer

104‧‧‧Second insulating polymer layer

200‧‧‧High frequency and high transmission double-sided copper foil substrate

201‧‧‧First copper foil layer

202‧‧‧Second copper foil layer

203‧‧‧First Very Low Dielectric Layer

204‧‧‧ Polyimine layer

205‧‧‧ LCP resin layer

206‧‧‧Another very low dielectric layer

Embodiments of the present invention are illustrated by way of example with reference to the accompanying drawings in which: FIG. 1 is a schematic structural diagram of the FRCC of the present invention; FIG. 2 is another schematic diagram of the FRCC of the present invention; and FIG. 3 is another embodiment of the FRCC of the present invention. A schematic diagram of a structure of a composite material for a flexible printed circuit board (FPC) of the present invention; and FIG. 5 is another method for fabricating a composite material for a flexible printed circuit board (FPC) of the present invention. Figure 6 is a schematic view of another process for the composite material of the present invention for a flexible printed circuit board (FPC); Figure 7 is a composite of the present invention for a flexible printed circuit board (FPC). Another schematic diagram of the material; Figure 8 is a schematic view of another method for fabricating a flexible printed circuit board (FPC) of the present invention; and Figure 9 is a flexible printed circuit board (FPC) of the present invention. A schematic diagram of another method of making a composite material.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily understand the advantages and functions of the present invention from the disclosure.

It is to be understood that the structure, the proportions, the size, and the like of the present invention are intended to be used in conjunction with the disclosure of the specification, and are not intended to limit the invention. The conditions are limited, so it is not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should remain in this book without affecting the effects and the objectives that can be achieved by the present invention. The technical content disclosed in the invention can be covered. In the meantime, the terms "first", "second", "one", "lower" and "upper" are used in the description, and are not intended to limit the scope of the invention. Changes or adjustments in the relative relationship are considered to be within the scope of the present invention. In addition, all ranges and values herein are inclusive and combinable. Any value or point falling within the ranges recited herein, such as any integer, may be the minimum or maximum value to derive the lower range and the like.

The invention provides a composite material for a flexible printed circuit board (FPC) The material comprises: a high-frequency high-transmission double-sided copper foil substrate having a first copper foil layer, a core layer sequentially formed on the surface of the first copper foil layer, and a second copper foil layer, wherein the core is formed The material of the layer is LCP resin or polyimine; and a backing soft copper foil substrate (FRCC) having a thickness of 8 to 185 μm is a third copper foil layer having a thickness of 1 to 35 μm, which is sequentially formed thereon. a second insulating polymer layer having a thickness of 5 to 100 μm on the surface of the third copper foil layer and a second very low dielectric adhesive layer having a thickness of 2 to 50 μm, and the backing soft copper foil substrate is The two-pole low dielectric adhesive layer is pressed together with the high-frequency high-transmission double-sided copper foil substrate; wherein the second insulating polymer layer is formed of at least one of the group consisting of polyimine and LCP resin; The second very low dielectric adhesive layer has a dielectric constant (Dk value) of 2.0 to 3.50, a dielectric loss (Df value) of 0.002 to 0.010; and the first copper foil layer and the second layer adjacent to the core layer The surface roughness of the surface of the copper foil layer is 0.05 to 0.5 μm and 0.1 to 1.10 μm, respectively.

Preferably, the surface roughness of the surface of the third copper foil layer adjacent to the second insulating polymer is 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9. Micron or 1.0 micron.

Preferably, the surface roughness of the surface of the second copper foil layer adjacent to the core layer is 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0. Micron, or 1.10 microns.

Preferably, the surface roughness of the surface of the first copper foil layer adjacent to the core layer is 0.1 micrometers, 0.2 micrometers, 0.3 micrometers, 0.4 micrometers, 0.5 micrometers.

Preferably, the second insulating polymer layer is a polyimide layer having a thickness of 5 to 50 μm; and the second insulating polymer layer is an LCP resin having a thickness of 5 to 100 μm.

Preferably, when the second insulating polymer layer is an LCP resin, the LCP resin has a dielectric constant (Dk value) of 2.0 to 3.50 and a dielectric loss (Df value) of 0.002 at a measurement frequency of 10 GHz. 0.0050 resin.

Preferably, the backing soft copper foil substrate has a water absorption of 0.01 to 1.5%.

Preferably, the first copper foil layer, the second copper foil layer and the third copper foil layer are independently selected from the group consisting of a rolled copper foil layer (RA/HA/HAV2) or an electrolytic copper foil layer (ED).

As shown in FIG. 1 , it is a specific embodiment of the adhesive backed flexible copper foil substrate of the composite material for a flexible printed circuit board (FPC) of the present invention. The thickness of the adhesive soft copper foil substrate is 8 to 185 micrometers, having a third copper foil layer 101 having a thickness of 1 to 35 micrometers, a second insulating polymer layer 103 sequentially formed on the surface of the third copper foil layer 101, and a second pole having a thickness of 10 to 50 micrometers A low dielectric adhesive layer 1022, and another extremely low dielectric adhesive layer 1021 formed between the third copper foil layer 101 and the second insulating polymer layer 103 and having a thickness of 10 to 50 microns.

The second insulating polymer layer 103 is a polyimide layer; the adhesive strength between the layers of the backing soft copper foil substrate is greater than 0.7 kg force/cm.

The material forming the second very low dielectric adhesive layer 1022 and the other extremely low dielectric adhesive layer 1021 is independently selected from the group consisting of a fluorine resin, an epoxy resin, an acrylic resin, a urethane resin, and a ruthenium rubber system. Resin, poly-p-xylene At least one of a group consisting of a resin, a bismaleimide resin, and a polyimide resin.

In this embodiment, the second very low dielectric adhesive layer is a thermosetting polyimine layer containing polyimine, and the polyimine content in the second very low dielectric adhesive layer is the first The total low solids weight of the dipolar low dielectric layer is 40 to 95% by weight.

According to the present invention, the second insulating polymer layer is made of a polyimide having a thickness of 5 to 12.5 μm; and the second insulating polymer layer is made of an LCP resin having a thickness of 12.5 to 50 μm; The two-pole low dielectric adhesive layer has a thickness of 10 to 50 microns. In this embodiment, the second insulating polymer layer 103 is a polyimide layer having a thickness of 5 to 12.5 microns.

In one embodiment, the adhesive backed flexible copper foil substrate may include a release layer (not shown) formed on the second very low dielectric adhesive layer relative to the second insulating polymer layer. The surface layer is a release film or a release paper, and the material of the release film is at least one selected from the group consisting of polypropylene, biaxially oriented polypropylene, and polyethylene terephthalate.

In this embodiment, the method for preparing the adhesive backed flexible copper foil substrate comprises the following steps: Step 1: Apply another extremely low dielectric adhesive layer 1021 to one side of the second insulating polymer layer 103, and Drying and pressing; step 2, pressing the third copper foil layer 101 on the upper surface of the other very low dielectric adhesive layer 1021; step 3, coating the second extremely low dielectric adhesive layer 1022 The cloth is formed on the other side of the second insulating polymer layer 103 and dried and pressed; in step 4, the release layer is pressed on the lower surface of the second very low dielectric adhesive layer 1022.

The preparation method of the adhesive back soft copper foil substrate, wherein the pre-pressing time is 10 to 20 seconds, the molding time is 60 to 120 seconds, the molding pressure is 90 to 110 kgf/cm 2 , and the pressing temperature is 175 to 195. °C, the curing temperature is 165 to 175 ° C, and the aging time is 50-60 minutes. Preferably, the molding pressure is 100 kgf/cm 2 , the aging temperature is 170 ° C, and the aging time is 60 minutes.

As shown in FIG. 2, another embodiment of the adhesive backed flexible copper foil substrate of the composite material for a flexible printed circuit board (FPC) of the present invention is shown. The thickness of the backed flexible copper foil substrate is 8 Up to 185 micrometers, there is a third copper foil layer 101, a second insulating polymer layer 103 and a second very low dielectric adhesive layer 102 sequentially formed on the surface of the third copper foil layer 101.

In this embodiment, the second insulating polymer layer 103 is a polyimide layer.

As shown in FIG. 3, another embodiment of the adhesive backed flexible copper foil substrate for a composite material of a flexible printed circuit board (FPC) of the present invention includes: a third copper foil layer 101, A second insulating polymer layer 104 (LCP resin layer) formed on the surface of the third copper foil layer 101 and a second very low dielectric adhesive layer 102 having a thickness of 10 to 50 μm are formed.

As shown in FIG. 4, in order to obtain the composite material of the composite material for a flexible printed circuit board (FPC) of the present invention, the second very low dielectric adhesive layer 1022 of the adhesive back flexible copper foil substrate 100 is pressed into the present invention. The invention has a high frequency high transmission double-sided copper foil substrate 200.

The preparation condition is that the adhesive back flexible copper foil substrate 100 and the high-frequency high-transmission double-sided copper foil substrate 200 are pre-compressed, pressed, and matured, wherein The pressing time is 10 to 30 seconds, the molding time is 120 to 180 seconds, the molding pressure is 90 to 110 kgf/cm 2 , the pressing temperature is 175 to 195 ° C, the curing temperature is 165 to 175 ° C, and the curing time is 50 to 60 minutes.

Preferably, the molding pressure is 100 kgf/cm 2 , the aging temperature is 170 ° C, and the aging time is 60 minutes.

In a specific embodiment, the preparation condition of the high-frequency high-transmission double-sided copper foil substrate 200 is 10 to 30 seconds, the molding time is 120 to 180 seconds, and the molding pressure is 90 to 110 kilograms per square. The centrifugation temperature is 175 to 195 ° C, the curing temperature is 165 to 175 ° C, and the curing time is 50 to 60 minutes.

In this embodiment, the obtained composite material for a flexible printed circuit board (FPC) composite material includes: the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention and the adhesive backed flexible copper foil substrate 100, The adhesive backing flexible copper foil substrate 100 comprises a third copper foil layer 101, another extremely low dielectric adhesive layer 1021 formed on the surface of the third copper foil layer 101, and a second comprising polyimine. An insulating polymer layer 103 and a second very low dielectric adhesive layer 1022, and the adhesive backed flexible copper foil substrate 100 is pressed against the high-frequency high-transmission double-sided copper foil substrate by the second extremely low dielectric adhesive layer 1022. The first copper foil layer 201 of 200.

In this embodiment, the high-frequency high-transmission double-sided copper foil substrate has a first copper foil layer 201, a first very low dielectric adhesive layer 203 sequentially formed on the surface of the first copper foil layer 201, Polyimide layer 204, another very low dielectric layer 206 and a second copper foil layer 202.

As shown in FIG. 5, in order to obtain another method for soft printing of the present invention The composite material of the composite material of the road board (FPC) is obtained by pressing the second ultra-low dielectric adhesive layer 1022 of the adhesive back flexible copper foil substrate 100 to the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention, wherein The preparation conditions are the same as in Fig. 4.

In this embodiment, the obtained composite material for a flexible printed circuit board (FPC) composite material includes: the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention and the adhesive backed flexible copper foil substrate 100, The adhesive backing flexible copper foil substrate comprises a third copper foil layer 101, another extremely low dielectric adhesive layer 1021 sequentially formed on the surface of the third copper foil layer 101, and a second insulation comprising polyimide. The polymer layer 103 and the second very low dielectric adhesive layer 1022, and the adhesive backed flexible copper foil substrate 100 is pressed against the high-frequency high-transmission double-sided copper foil substrate 200 by the second very low dielectric adhesive layer 1022. The first copper foil layer 201.

In this embodiment, the high-frequency high-transmission double-sided copper foil substrate has a first copper foil layer 201, an LCP resin layer 205 and a second copper foil layer sequentially formed on the surface of the first copper foil layer 201. 202.

As shown in FIG. 6, in order to obtain a composite material for a composite material of a flexible printed circuit board (FPC) according to the present invention, the second extremely low dielectric adhesive layer 102 of the backed flexible copper foil substrate 100 is pressed. In the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention, the preparation conditions are the same as in the fourth drawing.

In this embodiment, the obtained composite material for a flexible printed circuit board (FPC) composite material includes: the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention and the adhesive backed flexible copper foil substrate 100, The adhesive back flexible copper foil substrate comprises a third copper foil layer 101, a second insulating polymer layer 103 comprising polyimide, and a second low dielectric layer sequentially formed on the surface of the third copper foil layer 101. Electro-adhesive layer 102, and the adhesive backed flexible copper foil substrate 100 is The second very low dielectric adhesive layer 102 is pressed against the first copper foil layer 201 of the high frequency high transmission double-sided copper foil substrate 200.

In this embodiment, the high-frequency high-transmission double-sided copper foil substrate has a first copper foil layer 201, a first very low dielectric adhesive layer 203 sequentially formed on the surface of the first copper foil layer 201, Polyimide layer 204, another very low dielectric layer 206 and a second copper foil layer 202.

As shown in FIG. 7, in order to obtain a composite material for a composite material of a flexible printed circuit board (FPC) according to the present invention, the second extremely low dielectric adhesive layer 102 of the backed flexible copper foil substrate 100 is pressed. In the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention, the preparation conditions are the same as in the fourth drawing.

In this embodiment, the obtained composite material for a flexible printed circuit board (FPC) composite material includes: the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention and the adhesive backed flexible copper foil substrate 100, The adhesive back flexible copper foil substrate comprises a third copper foil layer 101, a second insulating polymer layer 103 comprising polyimide, and a second low dielectric layer sequentially formed on the surface of the third copper foil layer 101. The adhesive layer 102 is bonded to the first copper foil layer 201 of the high-frequency high-transmission double-sided copper foil substrate 200 by the second ultra-low dielectric adhesive layer 102.

In this embodiment, the high-frequency high-transmission double-sided copper foil substrate has a first copper foil layer 201, an LCP resin layer 205 and a second copper foil layer sequentially formed on the surface of the first copper foil layer 201. 202.

As shown in FIG. 8, in order to obtain a composite material for a composite material of a flexible printed circuit board (FPC) according to the present invention, the second extremely low dielectric adhesive layer 102 of the backed flexible copper foil substrate 100 is pressed. High frequency and high transmission in the invention The double-sided copper foil substrate 200, wherein the preparation conditions are the same as in the fourth drawing.

In this embodiment, the obtained composite material for a flexible printed circuit board (FPC) composite material includes: the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention and the adhesive backed flexible copper foil substrate 100, The adhesive back flexible copper foil substrate comprises a third copper foil layer 101, a second insulating polymer layer 104 comprising an LCP resin and a second very low dielectric adhesive sequentially formed on the surface of the third copper foil layer 101. The layer 102 and the backed flexible copper foil substrate 100 are pressed against the first copper foil layer 201 of the high-frequency high-transmission double-sided copper foil substrate 200 by the second very low dielectric adhesive layer 102.

In this embodiment, the high-frequency high-transmission double-sided copper foil substrate has a first copper foil layer 201, an LCP resin layer 205 and a second copper foil layer sequentially formed on the surface of the first copper foil layer 201. 202.

As shown in FIG. 9, in order to obtain a composite material for a composite material of a flexible printed circuit board (FPC) according to the present invention, the second extremely low dielectric adhesive layer 102 of the backed flexible copper foil substrate 100 is pressed. In the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention, the preparation conditions are the same as in the fourth drawing.

In this embodiment, the obtained composite material for a flexible printed circuit board (FPC) composite material includes: the high-frequency high-transmission double-sided copper foil substrate 200 of the present invention and the adhesive backed flexible copper foil substrate 100, The adhesive back flexible copper foil substrate comprises a third copper foil layer 101, a second insulating polymer layer 104 comprising an LCP resin and a second very low dielectric adhesive sequentially formed on the surface of the third copper foil layer 101. The layer 102 and the backed flexible copper foil substrate 100 are pressed against the first copper foil layer 201 of the high-frequency high-transmission double-sided copper foil substrate 200 by the second very low dielectric adhesive layer 102.

In this embodiment, the high-frequency high-transmission double-sided copper foil substrate has a first copper foil layer 201, and a first very low dielectric adhesive layer 203 sequentially formed on the surface of the first copper foil layer 201 ( a thermosetting polyimine layer containing a polyimine, and the polyamidene content is 72% by weight of the total solid content of the very low dielectric layer, the polyimide layer 204, and another very low dielectric The glue layer 206 and the second copper foil layer 202.

Table 1 and Table 2 are specific stacking and basic properties of the LCP substrates of Examples 1 to 10 and Comparative Examples 1 and 2, and Examples 1 to 4 are examples of the embodiment of Fig. 1; Examples 5 and 6 are embodiments of the embodiment of Fig. 2; and Examples 7 to 10 are examples of the embodiment of Fig. 3. The properties in the table are based on the "Soft Board Assembly Requirements Test Standard TPCA-F-002" as the test conditions, and the results are as follows.

In Table 1, the second very low dielectric adhesive layer and the other very low dielectric adhesive layer are each independently a thermosetting polyimide layer containing polyamidene, and the second very low dielectric adhesive layer The polyamidide content is 72% of the total solid content weight of the second very low dielectric layer; the polyethylenimine content of the other very low dielectric layer is the other very low dielectric The total solid content weight of the adhesive layer was 72%; the LCP substrate (50 um) of Comparative Example 1 was purchased from R-F705T 23RX-M substrate of Panasonic Corporation; and the LCP substrate (100 um) of Comparative Example 2 was purchased from Panasonic Corporation. R-F705T 43RX-M substrate.

The basic performance comparison between the specific embodiment of the specific embodiment of the present invention and the prior art LCP board is shown in Table 2 below.

It can be seen from Table 2 that the FRCC of the present invention has excellent performance, and therefore the composite material for a flexible printed circuit board (FPC) has excellent high-speed transmission property, low thermal expansion coefficient, and stable dielectric under high temperature and humidity environment. Constant/dielectric loss performance, ultra-low water absorption, good UV laser drilling capability, low resilience for high-density assembly, and excellent mechanical properties.

The invention is superior to the LCP film and the ordinary PI type bond sheet (Bond Sheet), and is suitable for wearable devices such as a 5G smart phone and an Apple watch.

In addition, in a specific embodiment of the present invention, the composite material for a flexible printed circuit board (FPC) includes a first copper foil layer, a second copper foil layer, and a third copper foil layer, and is composed of FRCC and high frequency. The double-sided copper foil substrate is laminated, wherein the third copper foil layer and the second copper foil layer are outer copper foil layers, which require high temperature (260 ° or so) soldering and mounting components, so the two peel strength requirements are higher (greater than 0.7 kg force / cm), and the first copper foil layer is located in the middle of the inner copper foil layer, also known as signal copper The foil layer is mainly used for the conduction line. It does not need to be mounted on SMT or other high-temperature process components. Therefore, the peel strength of the first copper foil layer and the second very low dielectric adhesive layer is required to be lower, and only needs to be greater than 0.5 kg force/ In the traditional concept, it has been considered that the bonding strength of the copper foil layer and other layers in the FPC is as large as possible (at least greater than 0.7 kgf/cm), and the less likely to delamination, the large bonding strength is generally The surface roughness value of the copper foil layer is required to be large, and since the copper foil layer has a skin effect during signal transmission, to achieve high frequency and high transmission, the surface roughness value of the copper foil layer needs to be as small as possible, so There is a contradiction between the large bonding strength and the high frequency high transmission, and the composite material of the composite material for the flexible printed circuit board (FPC) of the present invention does not need to pass the SMT or other high temperature process mounting components because the first copper foil layer does not need to be mounted. For the first copper foil layer and the second The peel strength of the very low dielectric adhesive layer is required to be lower than 0.5 kg force/cm, so the first copper foil layer can select copper with lower surface roughness value, better electrical properties and lower insertion loss. The foil layer does not affect the high frequency and high transmission of the FPC.

The above embodiments are merely illustrative and are not intended to limit the invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the present invention is defined by the scope of the appended claims, and should be construed as being

Claims (11)

A composite material for a flexible printed circuit board (FPC), comprising: a high-frequency high-transmission double-sided copper foil substrate having a first copper foil layer and a core layer sequentially formed on a surface of the first copper foil layer And a second copper foil layer, wherein the material forming the core layer is LCP resin or polyimine; and a backing soft copper foil substrate (FRCC) having a thickness of 8 to 185 μm, having a thickness of 1 to 35 μm a third copper foil layer, a second insulating polymer layer having a thickness of 5 to 100 micrometers and a second very low dielectric adhesive layer having a thickness of 2 to 50 micrometers, which are sequentially formed on the surface of the third copper foil layer, And the adhesive low-flexivity copper foil substrate is pressed into the high-frequency high-transmission double-sided copper foil substrate by the second extremely low dielectric adhesive layer; wherein the material of the second insulating polymer layer is formed by polyimine And at least one group consisting of LCP resins; the second very low dielectric layer has a dielectric constant (Dk value) of 2.0 to 3.50, a dielectric loss (Df value) of 0.002 to 0.010; and a proximity to the core The surface roughness of the surface of the first copper foil layer and the second copper foil layer of the layer is 0.05 to 0.5 micrometers and 0.1 to 1.10 micrometers, respectively. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the backing soft copper foil substrate has a water absorption ratio of 0.01 to 1.5%. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the first copper foil layer and the second copper foil The layer and the third copper foil layer are independently selected from the group consisting of a rolled copper foil layer or an electrolytic copper foil layer. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the LCP resin has a dielectric constant (Dk value) of 2.0 to 3.50 and a dielectric loss (Df value) of 0.002. To 0.0050. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the second insulating polymer layer and the third copper foil layer and the second very low dielectric adhesive layer Then the strength is greater than 0.7 kg force / cm. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the material for forming the second extremely low dielectric adhesive layer is selected from the group consisting of fluorine resin, epoxy resin, and acrylic resin. At least one of a group consisting of a resin, a urethane resin, a ruthenium rubber resin, a polyparaxylene resin, a bismaleimide resin, and a polyamidene resin. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the second very low dielectric adhesive layer is a thermosetting polyimine layer containing polyamidene, and the The polyamidimide content of the second very low dielectric layer is from 40 to 95% of the total solids weight of the second very low dielectric layer. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the adhesive back flexible copper foil substrate comprises a third copper foil layer and the second insulating polymer layer. Another very low dielectric adhesive layer between the third copper foil layer and the other very low dielectric adhesive The layer, the second insulating polymer layer and the second very low dielectric layer have a total thickness of 10 to 185 microns. The composite material for a flexible printed circuit board (FPC) according to claim 1, wherein the material of the second insulating polymer layer is made of polyimine, and the backing soft copper foil substrate is The total thickness is 8 to 135 microns. The composite material for a flexible printed circuit board (FPC) according to claim 1 or 8, wherein the high-frequency high-transmission double-sided copper foil substrate comprises a second-layer first-pole low-dielectric adhesive layer. Forming on opposite surfaces of the core layer to be respectively located between the first copper foil layer and the core layer and between the second copper foil layer and the core layer, and forming a material of the core layer amine. A method for preparing a composite material for a flexible printed circuit board (FPC) according to claim 1, comprising: pre-pressing the high-frequency high-transmission double-sided copper foil substrate and a back-coated soft copper foil substrate; And pressing and aging the high-frequency high-transmission double-sided copper foil substrate and the adhesive back flexible copper foil substrate, wherein the pre-pressing time is 10 to 30 seconds, the molding time is 120 to 180 seconds, and the molding pressure is 90 to 110 kgf/cm. ² , the pressing temperature is 175 to 195 ° C, the curing temperature is 165 to 175 ° C, and the curing time is 50 to 60 minutes.